Fix group assignment in votes matrix export

[colinmegill]

check base cluster for pid, check group for base cluster

[jucor]

@ballPointPenguin , as per @colinmegill request, flagging the ``.membersand.id` problem that are tripping the cypress-run test. It seems the fix has a wrong way to access the fields of `baseClusters`:

  function getGroupId(pid: number) {
    if (!baseClusters || !groupClusters) {
      return undefined;
    }

    // First find which base cluster contains this participant
    const baseClusterIds = baseClusters.id;
    const baseClusterMembers = baseClusters.members;
    let baseClusterId = -1;
    for (let i = 0; i < baseClusterIds.length; i++) {
      if (baseClusterMembers[i].includes(pid)) {
        baseClusterId = baseClusterIds[i];
        break;
      }
    }

    // If we found a base cluster, check which group contains it
    if (baseClusterId !== -1) {
      for (const group of groupClusters) {
        if (group.members.includes(baseClusterId)) {
          return group.id;
        }
      }
    }

    return undefined;
  }

The code runs as is, but we do get a linter error.
@colinmegill told me to flag it but leave the fix of the fix up to you @ballPointPenguin . (and indeed I tried a first fix-of-the-fix, which broke the fix, then again I don't know TypeScript and haven't coded in Javascript since 1999 :P)

[jucor]

I confirm that:
1/ I could repro the bug: on edge branch,

(polis-data-dive) julien@Juliens-MacBook-Pro:edge$ time csvstat -c 2  2025-02-27-1444-[ZINVITE]-participant-votes.csv 
  2. "group-id"

        Type of data:          Boolean
        Contains null values:  True (excluded from calculations)
        Non-null values:       100
        Unique values:         3
        Most common values:    None (3247x)
                               True (75x)
                               False (25x)

Row count: 3347

real    0m18.568s
user    0m18.055s

2/ this pull-request as it is fixes the bug (even with the typescript warning discussed above -- there must be a tolerance in typescript :) ):

(polis-data-dive) julien@Juliens-MacBook-Pro:post-fix$ time csvstat -c 2  2025-02-27-1455-[ZINVITE]-participant-votes.csv 
  2. "group-id"

        Type of data:          Boolean
        Contains null values:  True (excluded from calculations)
        Non-null values:       2693
        Unique values:         3
        Most common values:    True (2495x)
                               None (654x)
                               False (198x)

Row count: 3347

real    0m18.183s
user    0m17.805s
sys     0m0.203s

Thanks @metasoarous for the clear report, and @colinmegill for coding the fix.
@ballPointPenguin Can you merge please? (with or without the minor typescript fix above, up to you)

[jucor]

@ballPointPenguin Ah, I think I know why Colin's code works in spite of the linter error. His code respects the actual structure of the JSON, as illustrated by @metasoarous in the screenshots here: #1930 (comment)

That's why it works. So I suspect it's only somewhere the Typescript type definition for baseClusters (a few lines above getGroupId) that does not respect the JSON format. And I'm completely ignorant of Typescript, but I imagine that at least in some cases the reality of the object overrides the types?

[jucor]

So I believe (but haven't tested) that the right type should be:

const baseClusters: { id: number[]; members: number[][] } | undefined = pca?.asPOJO["base-clusters"];

Actually, give me a second and I'll test the export with that modification.

[jucor]

Yup, confirmed, with the modified type I describe above the linter is happy and the export is still good :)

(polis-data-dive) julien@Juliens-MacBook-Pro:post-fix-with-correct-type$ time csvstat -c 2  2025-02-27-1720-[ZINVITE]-participant-votes.csv 
  2. "group-id"

        Type of data:          Boolean
        Contains null values:  True (excluded from calculations)
        Non-null values:       2693
        Unique values:         3
        Most common values:    True (2495x)
                               None (654x)
                               False (198x)

Row count: 3347

real    0m18.549s
user    0m17.712s
sys     0m0.200s

I don't know how to edit this PR as I don't have push access to the polis repo, so I'll let you do it :)

[ballPointPenguin]

Updated this PR with cleanup and fixes.